Parmandur
Book-Friend, he/him
Of course, this subclass variety is relatively minor and only goes so far, with most subclasses merely shuffling around where you get advantage and new ribbon abilities.
The only real way to add true variety is to add new full classes, and I fully sympathize with the original poster's possible shock at hearing that no new classes have yet seen official publication a full five years after 5E release.
If they had a few dozen Classes, the differences would be pretty minor after a certain point (see also, 3.x). The Class-Subclass system allows for greater control and focus while allowing for a wide narrative varity.